/**
 * @author haina.z@163.com
 * @brief crc8
 * @version V1.0
 */

/** Includes -----------------------------------------------------------------*/
#include "crc8.h"

/** Macros and constants -----------------------------------------------------*/
#define CRC8_INIT_VALUE                                     0x00

/** Type definitions ---------------------------------------------------------*/

/** Private variable definitions (static) ------------------------------------*/
// CRC8查表法, Init: 0x00, Poly: 0x07
static const uint8_t Crc8_Table[] =
{
    0x00, 0x07, 0x0e, 0x09, 0x1c, 0x1b, 0x12, 0x15,
    0x38, 0x3f, 0x36, 0x31, 0x24, 0x23, 0x2a, 0x2d,
    0x70, 0x77, 0x7e, 0x79, 0x6c, 0x6b, 0x62, 0x65,
    0x48, 0x4f, 0x46, 0x41, 0x54, 0x53, 0x5a, 0x5d,
    0xe0, 0xe7, 0xee, 0xe9, 0xfc, 0xfb, 0xf2, 0xf5,
    0xd8, 0xdf, 0xd6, 0xd1, 0xc4, 0xc3, 0xca, 0xcd,
    0x90, 0x97, 0x9e, 0x99, 0x8c, 0x8b, 0x82, 0x85,
    0xa8, 0xaf, 0xa6, 0xa1, 0xb4, 0xb3, 0xba, 0xbd,
    0xc7, 0xc0, 0xc9, 0xce, 0xdb, 0xdc, 0xd5, 0xd2,
    0xff, 0xf8, 0xf1, 0xf6, 0xe3, 0xe4, 0xed, 0xea,
    0xb7, 0xb0, 0xb9, 0xbe, 0xab, 0xac, 0xa5, 0xa2,
    0x8f, 0x88, 0x81, 0x86, 0x93, 0x94, 0x9d, 0x9a,
    0x27, 0x20, 0x29, 0x2e, 0x3b, 0x3c, 0x35, 0x32,
    0x1f, 0x18, 0x11, 0x16, 0x03, 0x04, 0x0d, 0x0a,
    0x57, 0x50, 0x59, 0x5e, 0x4b, 0x4c, 0x45, 0x42,
    0x6f, 0x68, 0x61, 0x66, 0x73, 0x74, 0x7d, 0x7a,
    0x89, 0x8e, 0x87, 0x80, 0x95, 0x92, 0x9b, 0x9c,
    0xb1, 0xb6, 0xbf, 0xb8, 0xad, 0xaa, 0xa3, 0xa4,
    0xf9, 0xfe, 0xf7, 0xf0, 0xe5, 0xe2, 0xeb, 0xec,
    0xc1, 0xc6, 0xcf, 0xc8, 0xdd, 0xda, 0xd3, 0xd4,
    0x69, 0x6e, 0x67, 0x60, 0x75, 0x72, 0x7b, 0x7c,
    0x51, 0x56, 0x5f, 0x58, 0x4d, 0x4a, 0x43, 0x44,
    0x19, 0x1e, 0x17, 0x10, 0x05, 0x02, 0x0b, 0x0c,
    0x21, 0x26, 0x2f, 0x28, 0x3d, 0x3a, 0x33, 0x34,
    0x4e, 0x49, 0x40, 0x47, 0x52, 0x55, 0x5c, 0x5b,
    0x76, 0x71, 0x78, 0x7f, 0x6a, 0x6d, 0x64, 0x63,
    0x3e, 0x39, 0x30, 0x37, 0x22, 0x25, 0x2c, 0x2b,
    0x06, 0x01, 0x08, 0x0f, 0x1a, 0x1d, 0x14, 0x13,
    0xae, 0xa9, 0xa0, 0xa7, 0xb2, 0xb5, 0xbc, 0xbb,
    0x96, 0x91, 0x98, 0x9f, 0x8a, 0x8d, 0x84, 0x83,
    0xde, 0xd9, 0xd0, 0xd7, 0xc2, 0xc5, 0xcc, 0xcb,
    0xe6, 0xe1, 0xe8, 0xef, 0xfa, 0xfd, 0xf4, 0xf3
};

/** Static function declarations (prototypes) --------------------------------*/

/** Public variable definitions ----------------------------------------------*/

/** Pre-compile check --------------------------------------------------------*/

/** Code ---------------------------------------------------------------------*/

/**
 * @brief 初始化CRC8
 * 
 * @param pCrc8 当前CRC变量的地址
 */
void CRC8_Init(uint8_t *pCrc8)
{
    *pCrc8 = CRC8_INIT_VALUE;
}

/**
 * @brief 更新CRC8
 * 
 * @param pCrc8 当前CRC变量的地址
 * @param u8New 新值
 */
void CRC8_UpdateWithPoly(uint8_t *pCrc8, uint8_t u8New)
{
    uint8_t u8Crc, i;

    u8Crc = *pCrc8 ^ u8New;
    for (i = 0; i < 8; i++)
    {
        if (u8Crc & 0x80)
        {
            u8Crc = (u8Crc << 1) ^ 0x07;
        }
        else
        {
            u8Crc <<= 1;
        }
    }
    *pCrc8 = u8Crc;
}

void CRC8_UpdateWithTable(uint8_t *pCrc8, uint8_t u8New)
{
    *pCrc8 = Crc8_Table[*pCrc8 ^ u8New];
}

/**
 * @brief 计算CRC8值
 * 
 * @param pDat 起始地址
 * @param u16Len 计算的长度
 * @return uint8_t 返回CRC8值
 */
uint8_t CRC8_CalculateWithPoly(const uint8_t *pDat, uint16_t u16Len)
{
    // Init: 0x00, Poly: 0x07
    uint8_t u8Crc = CRC8_INIT_VALUE;
    uint8_t i;

    while (u16Len--)
    {
        u8Crc ^= *pDat++;
        for (i = 0; i < 8; i++)
        {
            if (u8Crc & 0x80)
            {
                u8Crc = (u8Crc << 1) ^ 0x07;
            }
            else
            {
                u8Crc <<= 1;
            }
        }
    }

    return u8Crc;
}

uint8_t CRC8_CalculateWithTable(const uint8_t *pDat, uint16_t u16Len)
{
    uint8_t u8Crc = 0x0;

    while (u16Len--)
    {
        u8Crc = Crc8_Table[u8Crc ^ *pDat++];
    }

    return u8Crc;
}

/******************************** End of file *********************************/
